Artificial Intelligence: AI seems to be having a PR resurgence since Google bought DeepMind in early 2014. The applications in health are broad and with huge potential. This list tracks notable companies that focus partially or completely on applying AI to health.

Advanced Analytics: A forward-looking style of information analysis focused on continuous and iterative investigation of past performance to drive business planning and estimate future performance. Predictive modeling is perhaps the most widley recognized technique in this category, but there are others. This list contains information around Advanced Analytics news, resources and offerings.

Transition of Care: Read this for background. I actually consider care transition to be a part of enterprise Electronic Health Records (EHRs), but there have recently been a number of companies that are focused on creating solutions for managing the transition of patient from one care setting to another (e.g. discharge from inpatient facility to home or PCP care). This list doesn't include the traditional EHR vendors.

Care Collaboration: Solutions that focus on making it easier for different caregivers (family, relatives, clinicians, etc.) and teams to work with one other in context of a single patient's care. Like Transition of Care, this is something that conventional enterprise EHRs would ideally provide, but niche companies are emerging focused on just this value proposition. Also note that the line between care collaboration and transition of care solutions is bit blurry. There is no consensus or explicit definition, but from my perspective, both belong to the overall topic of Care Coordination.

Population Health Management: Healthcare IT software related to managing a large group of patients. Includes vendors offerings that have to do with registries, research cohorts, patient panel management, etc.

Communication: With the market focus on interop and care transition, several firms have started claiming to solve the communication-silo problem in healthcare. Real-time, secure exchange of messages across organizational and team boundaries is an inspiring dream. Current approaches to it span HIE names, Secure Texting vendors, Secure Emailing etc.

Narrow Topics

Clinical Domain Specific: Some of the interesting companies have chosen a particular clinical specialty as their target market. Like Dermatology, Mental Health. Offerings typically include marketplaces, telemedicine, etc.

Niche Healthcare IT Companies: Firms offering specialized, sometimes informatics-heavy products. Most have not seen significant market traction. They are noted here because of the somewhat unique pedigree or solution or target market. Mostly, they focus on opportunities not directly addressed by big players in Healthcare IT industry.

Scheduling: Some offerings in the market are specifically focusing on scheduling issues in healthcare. They range from the often-thought-about topic of patient appointment scheduling, to less-known but more intricate topic of staff scheduling. Scheduling is potentially a future sub-domain that can sustain independent yet viable vendors.

Medication Related: A curious sub-category that can fit in couple of parent categories elsewhere. Extracted here to study on it's own since it has the special property of crossing care settings very easily (meds remain a relevant context before, during and after a healthcare encounter). There has been an upsurge in medication-related startups in the recent past.

Digital Medicine: Buzzword-like category to keep track of companies that are creating software interventions that may qualify as actual clinical interventions (diagnostic, therapeutic) one day.

Insurance: Startups that are disrupting the traditional health insurance carrier industry, using new approaches like digital tools, prevention focus, customer service etc.

Hardware Platforms: These are (were) the players putting forth physical computing devices with healthcare focus (eg. built to withstand bumps, disinfection, spills etc). This category was fascinating in early 2000's, but now mostly lifeless. Preserved only for bemusement and posterity.